The invention herein involves the capture and treatment of excess uncured paint which is produced during spray painting operations. In particular, the invention relates to compositions which detackify excess spray paint and a process for utilizing these compositions in the environment of an industrial spray booth.
Typically, manufactured articles receive one or more coats of paint during the production process. Paint is usually applied using a paint sprayer which reduces liquid paint to minute particles and then propels these particles onto the article surface. While this method applies a thin, even coat of paint on the article, a significant amount of excess paint is also deposited on surfaces surrounding the article such as walls and floors.
In industrial settings, the paint spraying operation usually takes place inside a paint spray booth into which an article is typically carried by a conveyor belt. When the article is positioned in the booth, paint sprayers are activated to apply a coat of paint. The excess or "overspray" paint produced during the paint spraying operation adheres to the wall surfaces of the spray booth as well as on conveyor belt components and the like. During successive paint applications, layer upon layer of tarry, uncured paint accumulate on these booth surfaces. To prevent the paint build-up from interfering with the paint application process and from creating a fire hazard, the paint must be periodically removed or, alternatively, the build-up must somehow be prevented.
In order to remove the excess uncured paint build-up, the production process must be halted to allow workers to enter the paint booth with various cleaning devices to laboriously extract the layers of paint. The paint build-up is typically removed through the use of highly flammable organic solvents which may give off poisonous vapors and which often yield environmentally toxic substances. This down-time and the expense, effort and hazard associated with the use of flammable organic solvents, make their use in the paint removal process highly undesirable.
Many industrial paint booths are now equipped with devices which "capture" the paint overspray in a wall of recirculating water before the overspray can adhere to booth surfaces. These "water-walls" or "water curtains", as they are known, are placed between the article to be painted and booth surfaces so that as the paint overspray enters the sheet of circulating water, it is carried into tanks located below the spray booth. Pumps then recirculate the water through the water curtain. Although water-walls are effective in preventing significant build-up of paint on spray booth surfaces, the captured paint remains tacky in water, thus tending to coalesce and adhere to those surfaces with which it comes in contact. The paint accumulates on tank walls and other surfaces, often clogging pipes, pumps, filters and the like. Much of the paint overspray settles out of the water to the floor of the tank where it forms a layer of tarry paint sometimes several feet thick. This paint build-up in the tank must then be removed, again resulting in production down-time, clean-up expense, and the hazards associated with the use of flammable, toxic, organic solvents. While it is known to treat overspray with clays or other bulky chemicals to facilitate paint removal, none of these conventional compositions and methods have produced satisfactory results.